TY - JOUR
T1 - Customized biochar for soil applications in arid land
T2 - Effect of feedstock type and pyrolysis temperature on soil microbial enumeration and respiration
AU - Al-Rabaiai, Ahmed
AU - Menezes-Blackburn, Daniel
AU - Al-Ismaily, Said
AU - Janke, Rhonda
AU - Pracejus, Bernhard
AU - Al-Alawi, Ahmed
AU - Al-Kindi, Mohamed
AU - Bol, Roland
N1 - Funding Information:
This work was funded by a grant from Sultan Qaboos University entitled: Integrating modern soil and water smart technologies for salinity management in the Sultanate of Oman , His Majesty Fund ( SR/AGR/SWAE /21/01 ). The authors appreciate the additional in-kind support from SQU, Oman.
Publisher Copyright:
© 2022 Elsevier B.V.
PY - 2022/11
Y1 - 2022/11
N2 - Biochar is rapidly gaining worldwide interest as an agro-technology for increasing soil health and carbon storage. This study investigated the physicochemical characteristics and impact on soil microbes of biochar amendments from three feedstock sources: date palm leaves (D), mesquite plants (M) and sludge compost (S.C.); pyrolyzed at 450 ℃, 600 ℃ and 750 ℃. Scanning electron microscopy images showed an apparent pore size increase with increasing pyrolysis temperature. The increase in pyrolysis temperature decreased O-H and C-O bonds and increased the proportion of C-C bonds, as obtained from the Fourier transform infrared spectroscopy studies. Thermostability was highest at a pyrolysis temperature of 750 ℃, with distinct thermal decomposition profiles for each of the three feedstock materials used, as indicated by the dynamic thermal gravimetric analysis. The SC biochars showed the highest mineral content (45–66%) with significantly higher water-soluble and total concentrations of mineral elements. The SC samples also showed the presence of possible soil contaminants such as Pb and As, and its use as a soil amendment is not recommended, even though the SC at 450 ℃ was the only nonalkaline biochar in this study. The M feedstock produced biochar with the highest surface area (600 m2 g−1) and carbon content based on loss on ignition (94.98%); nevertheless, the M biochar reduced soil microbial enumeration and respiration. This reduction increased with increasing pyrolysis temperature. Therefore, the M biochar feedstocks are not recommended for improving soil health and may be tested in the future as a microbial inhibitor for soil-borne plant pathogens. Considering the physicochemical properties and the biochar impact on soil, D at 600 ℃ was the best biochar selected for further studies as a soil amendment. The large differences in biochar physicochemical properties and their effect on soil microbes observed in this study suggest that the feedstock type and pyrolysis temperatures must be considered during biochar amendment production for improving soil health in arid-land agroecosystems.
AB - Biochar is rapidly gaining worldwide interest as an agro-technology for increasing soil health and carbon storage. This study investigated the physicochemical characteristics and impact on soil microbes of biochar amendments from three feedstock sources: date palm leaves (D), mesquite plants (M) and sludge compost (S.C.); pyrolyzed at 450 ℃, 600 ℃ and 750 ℃. Scanning electron microscopy images showed an apparent pore size increase with increasing pyrolysis temperature. The increase in pyrolysis temperature decreased O-H and C-O bonds and increased the proportion of C-C bonds, as obtained from the Fourier transform infrared spectroscopy studies. Thermostability was highest at a pyrolysis temperature of 750 ℃, with distinct thermal decomposition profiles for each of the three feedstock materials used, as indicated by the dynamic thermal gravimetric analysis. The SC biochars showed the highest mineral content (45–66%) with significantly higher water-soluble and total concentrations of mineral elements. The SC samples also showed the presence of possible soil contaminants such as Pb and As, and its use as a soil amendment is not recommended, even though the SC at 450 ℃ was the only nonalkaline biochar in this study. The M feedstock produced biochar with the highest surface area (600 m2 g−1) and carbon content based on loss on ignition (94.98%); nevertheless, the M biochar reduced soil microbial enumeration and respiration. This reduction increased with increasing pyrolysis temperature. Therefore, the M biochar feedstocks are not recommended for improving soil health and may be tested in the future as a microbial inhibitor for soil-borne plant pathogens. Considering the physicochemical properties and the biochar impact on soil, D at 600 ℃ was the best biochar selected for further studies as a soil amendment. The large differences in biochar physicochemical properties and their effect on soil microbes observed in this study suggest that the feedstock type and pyrolysis temperatures must be considered during biochar amendment production for improving soil health in arid-land agroecosystems.
KW - Biochar pyrolysis
KW - Feedstock quality
KW - Mesquite trees
KW - Organic waste
KW - Soil health
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U2 - 10.1016/j.jaap.2022.105693
DO - 10.1016/j.jaap.2022.105693
M3 - Article
AN - SCOPUS:85138086716
SN - 0165-2370
VL - 168
JO - Journal of Analytical and Applied Pyrolysis
JF - Journal of Analytical and Applied Pyrolysis
M1 - 105693
ER -